I should probably rephrase my previous message: @glasgow is absolutely right to report it as a bug - it’s inconsistent with the normally expected behaviour.
I suppose I was more after education about why it’s a problem, rather than policing how different people use the app!
All of my direct debits do this.
e.g. both of my phone bills show my account number and my car finance shows the reg and agreement number. It’s down to whatever’s sent through as the payment reference and in AMEX’s case they send through the card number.
If it’s an issue you can open the transaction, tap the notes section to edit then delete the number.